From self-sufficiency to synergy: Decarbonizing industrial park process heat with biomass steam export and grid-interactive heat pumps

Industrial process heat is both carbon-intensive and increasingly dependent on the power system for deep decarbonization. In the context of rising shares of renewable electricity, flexible and low-carbon heat supply solutions are urgently needed to ensure reliable and economical operation. This study develops a full-year, park-boundary optimization framework that integrates two forms of synergy: (i) grid-interactive steam-generating heat pumps with thermal storage, and (ii) cross-plant allocation and trading of biomass steam. Within this framework, cost, exergy performance, and operational flexibility are quantitatively evaluated and translated into implementable planning rules. Results show that heat pumps with storage incur a modest exergy penalty because of higher condensation temperatures and temperature-varying heat exchange. Even so, they reduce the levelized cost of heat by shifting over 70 % of electricity consumption to low-price hours. Park-level coordination outperforms mill-level self-sufficiency. Biomass steam is dispatched to high-temperature demands, whereas heat pumps upgrade external nuclear waste heat for medium- and low-temperature loads. The optimized configuration achieves a fully zero-carbon heat supply, avoids 3.63 million t of carbon dioxide emissions annually, and delivers a levelized cost of 67.7 CNY/GJ, below the 100–120 CNY/GJ cost of natural-gas boilers. Sensitivity analysis to electricity tariff structures indicates that larger peak-to-valley ratios enhance economic performance. From these findings, practical rules are derived for energy planning, biomass allocation, and SGHP configuration. The framework is transferable to other industrial parks by substituting local zero-carbon waste-heat sources and economic parameters, offering guidance for zero-carbon heat-system planning and industrial demand response.